docs(subagent): record the public interrupt in the continuation contract docs

The continuable-subagent core-data page and the continuation lifecycle
Agent Note claimed no public subagent cancellation existed; interrupt()
is now that one public stop. Both pages and their Chinese counterparts
state the shipped contract and link the owning interrupt note.

Refs #1535

docs/core-data-structures/subagent.i18n.yaml

@@ -2,5 +2,5 @@
 # side as of the last confirmed-consistent state. Both languages carry equal authority;
 # after editing either side, bring the other along and re-record with:
 #   pnpm run verify-translation-pairing --write docs/core-data-structures/subagent.md
-subagent.md: 4d7552eb5749284d90e31e62d8ac02e3d7a21b1d
-subagent.zh.md: ebcb1ce445c164352109d6613028c7a36c10d6d4
+subagent.md: fba934233fb7e890d6a68bd4cc7d37f90ab913ed
+subagent.zh.md: 70651397f82e2cf4c0fe18aa26ff8247484ca0aa

docs/core-data-structures/subagent.md

@@ -139,7 +139,20 @@ The Agent inbox is the only queue. Every continuation message becomes one `Agent
 
 Follow-up authority comes from an exact live Agent tool context. The authenticated Agent must be the durable child's direct parent recorded in `SessionHeader.parentSession`. `MessageSource` and `senderSessionId` are durable provenance after admission and grant no authority; the optional model-facing tool uses `CoordinatorMessageSource`.
 
-For both operations the caller signal owns lookup, materialization, and admission only until inbox acceptance. Afterwards the manager owns the Activation independently: later caller cancellation neither cancels the accepted turn nor disposes the child, and the seam exposes no public subagent cancellation or steering operation.
+For both operations the caller signal owns lookup, materialization, and admission only until inbox acceptance. Afterwards the manager owns the Activation independently: later caller cancellation neither cancels the accepted turn nor disposes the child, and the seam exposes no steering operation.
+
+`SubagentService.interrupt(targetSessionId, authority)` is the one public stop: it authorizes synchronously, issues `Agent.cancel(cause, { keepInbox: true })` on the live target, and returns without awaiting quiescence. The Activation, its pending inbox work, and published descendants are untouched; only a later waking send resumes the parked FIFO queue. An absent target — unknown, one-shot, or already settled — and a manager-less composition are accepted no-ops; a wrong parent address or a stale, self-targeting, or non-ancestor caller rejects with `UNAUTHORIZED`.
+
+```ts type-equiv
+/**
+ * Authority under which one interrupt request is admitted. `user` carries the
+ * durable direct-parent address a human client presented; `ancestor` carries
+ * the exact live Agent object whose recorded lineage must contain the caller.
+ */
+type SubagentInterruptAuthority =
+  | { readonly kind: 'user'; readonly parentSessionId: SessionId }
+  | { readonly kind: 'ancestor'; readonly agent: Agent }
+```
 
 Every Activation owns its `AgentHandle` and an `ownedChildren: Set<SessionId>`; because one Session has at most one live Activation, the child Session id identifies the live child without another runtime-incarnation reference. Starting a child or submitting parent-originated work registers the child in a continuation-managed parent's set before the child can run, and that parent cannot settle while the set is non-empty. A top-level or other non-continuation Agent has no Activation and stays outside the waiting graph. Child release happens only after the child Agent is quiescent, every child of that child is disposed, the best-effort final session flush settles, and the child's `AgentHandle` completes disposal.
 

docs/core-data-structures/subagent.zh.md

@@ -139,7 +139,20 @@ Agent 收件箱是唯一的队列。每条继续执行消息都会成为一个 `
 
 后续操作的权限来自确切的在线 Agent 工具上下文。已认证的 Agent 必须是持久化子 agent 在 `SessionHeader.parentSession` 中记录的直接父级。`MessageSource` 与 `senderSessionId` 在准入之后是持久的来源凭据，不授予任何权限；可选的面向模型工具使用 `CoordinatorMessageSource`。
 
-对于这两种操作，调用方 signal 仅在收件箱接受之前掌管查找、物化与准入。此后管理器独立掌管该 Activation：之后的调用方取消既不会取消已接受的轮次，也不会 dispose 子 agent，并且该 seam 不对外暴露任何 subagent 取消或 steering（中途引导）操作。
+对于这两种操作，调用方 signal 仅在收件箱接受之前掌管查找、物化与准入。此后管理器独立掌管该 Activation：之后的调用方取消既不会取消已接受的轮次，也不会 dispose 子 agent，并且该 seam 不对外暴露任何 steering（中途引导）操作。
+
+`SubagentService.interrupt(targetSessionId, authority)` 是唯一的公开停止操作：它同步完成鉴权，对在线目标发出 `Agent.cancel(cause, { keepInbox: true })`，然后不等待静止即返回。Activation、其待处理的 inbox 工作与已发布的后代均不受影响；只有之后的一次唤醒发送才会恢复被暂停的 FIFO 队列。不存在的目标——未知、一次性或已结算——以及未绑定管理器的组合是被接受的 no-op；错误的 parent 地址，或过期、指向自身、非 ancestor 的调用方会以 `UNAUTHORIZED` 拒绝。
+
+```ts type-equiv
+/**
+ * Authority under which one interrupt request is admitted. `user` carries the
+ * durable direct-parent address a human client presented; `ancestor` carries
+ * the exact live Agent object whose recorded lineage must contain the caller.
+ */
+type SubagentInterruptAuthority =
+  | { readonly kind: 'user'; readonly parentSessionId: SessionId }
+  | { readonly kind: 'ancestor'; readonly agent: Agent }
+```
 
 每个 Activation 都拥有自己的 `AgentHandle` 和一个 `ownedChildren: Set<SessionId>`；由于一份会话至多有一个存活 Activation，子会话 id 无需另一个运行时化身引用即可标识存活的子 agent。启动子 agent 或提交源自 parent 的工作，会在子 agent 能够运行之前将其注册到受继续执行管理的父级集合中；只要该集合非空，该父级就无法 settle。顶层或其他非继续执行的 Agent 没有 Activation，处于 waiting 图之外。只有当子 Agent 已停稳、该子 agent 的每个子级都已 dispose、best-effort 的最终会话 flush 结算完毕，且子 agent 的 `AgentHandle` 完成 dispose 之后，才会释放子 agent。